We plan to study the molecular structure and expression of mammalian preproinsulin genes. Structural information concerning this defined model system could contribute to the understanding of the molecular mechanisms involved in transcriptional regulation and of the pathogenesis of spontaneous diabetes mellitus. We will first determine the entire primary structure of mature preproinsulin mRNA (only part of which has been established to date) and map it on chromosomal DNA. The chromosomal arrangement of prepro-insulin genes will be determined by restriction endonuclease analysis and DNA sequencing of long stretches of cloned rat and human chromosomal DNA containing the coding regions of these genes, together with associated sequences, and will be compared to that of spontaneously diabetic animal models. As a first step for further studies on transcription we propose to study the structure of the primary transcripts of these genes by S1 nuclease mapping and RNA blotting. We are also interested to examine whether or not D-glucose (a physiological signal for insulin biosynthesis and release) stimulates transcription of preproinsulin mRNA in isolated pancreatic islets in organ cultures.